如何转换std :: chrono :: time_point到日历datetime字符串与小数秒？ [英] How to convert std::chrono::time_point to calendar datetime string with fractional seconds?

问题描述

如何将std :: chrono :: time_point转换为带分数秒的日历datetime字符串？
例如：10-10-2012 12：38：40.123456。

How to convert std::chrono::time_point to calendar datetime string with fractional seconds? For example: "10-10-2012 12:38:40.123456".

推荐答案

如果是system_clock，有time_t转换。

If system_clock, this class have time_t conversion.

#include <iostream>
#include <chrono>
#include <ctime>

using namespace std::chrono;

int main()
{
  system_clock::time_point p = system_clock::now();

  std::time_t t = system_clock::to_time_t(p);
  std::cout << std::ctime(&t) << std::endl; // for example : Tue Sep 27 14:21:13 2011
}

示例结果：

Thu Oct 11 19:10:24 2012

编辑：
但是，time_t不包含小数秒。
另一种方法是使用time_point :: time_since_epoch（）函数。此函数从epoch返回持续时间。
跟随示例是毫秒秒分辨率。

But, time_t does not contain fractional seconds. Alternative way is to use time_point::time_since_epoch() function. This function returns duration from epoch. Follow example is milli second resolution's fractional.

#include <iostream>
#include <chrono>
#include <ctime>

using namespace std::chrono;

int main()
{
  high_resolution_clock::time_point p = high_resolution_clock::now();

  milliseconds ms = duration_cast<milliseconds>(p.time_since_epoch());

  seconds s = duration_cast<seconds>(ms);
  std::time_t t = s.count();
  std::size_t fractional_seconds = ms.count() % 1000;

  std::cout << std::ctime(&t) << std::endl;
  std::cout << fractional_seconds << std::endl;
}

示例结果：

Thu Oct 11 19:10:24 2012

925

这篇关于如何转换std :: chrono :: time_point到日历datetime字符串与小数秒？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！